Possible Causes & Corrections

Check the following items:

• Check exhaust system for restrictions, such as a damaged or collapsed pipe, muffler or catalytic converter. See EXHAUST SYSTEM BACKPRESSURE under MECHANICAL INSPECTION in appropriate BASIC DIAGNOSTIC PROCEDURES article.
• Check engine compression. Check for incorrect valve timing, bent push rods, broken valve springs or worn camshaft lobes.
• Check fuel injectors. Perform injector balance test. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article.
• Check fuel system for incorrect fuel pressure. See BASIC FUEL SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
• Check for items that cause the engine to run rich, or lean.
• Check transmission shift solenoid system and Torque Converter Clutch (TCC) system for proper operation.
• Using Spark Tester (J-26792), check for adequate spark output.
• Ensure correct initial ignition timing.
• Check Knock Sensor (KS) system for excessive retard.
• Check air filter and fuel filter. Replace if necessary.
• Check for poor fuel quality or water-contaminated fuel.
• Check fuel injector wires for short to ground at air cleaner.
• Check PCM grounds. Ensure they are clean, tight and properly located.
• Ensure EGR valve is not stuck open.
• Check for proper operation of the Transmission Fluid Pressure (TFP) manual valve switch.
• Check charging system output. Repair if output is less than 9 volts or greater than 16 volts.
• Check A/C for proper operation.
• Check for conditions that cause the engine torque management system to reduce engine power.